Contact and pressure-lock terminal



Sept. 13, 1960 M. EHRLICH CONTACT AND PRESSURE-LOCK TERMINAL Filed July18, 1957 INVENTOR MA X/M/L m/v Ema ICH am /51% fl ATTO RN EYS UnitedStates PatentfQ CONTACT AND PRESSURE-LOCK TERMINAL Maximilian Ehrlich,Baldwin, N.Y., assignor to Leviton Manufacturing Co., Inc., Brooklyn,N.Y., a corporation of New York Filed July 18, 1957, Ser. No. 672,628

6 Claims. (Cl. 339-95) 4, 2,952,831 Patented Sept. ,13, 1961 F icecontact blade of an attachment plug (not shown) to be insertedtherebetween and the resilience of the mate- 2,705,785 dated April 5,1955. An object of the invenv tion is to simplify the construction ofsuch a terminal and thereby to reduce manufacturing costs for a wiringdevice in which such a terminal is employed.

In a contact and pressure-lock terminal made in accordance with thepresent invention, the wire-engaging members, the terminal portions andthe contact elements are permanently connected to each other,'beingformed integrally from the same stock and separate members of specialshape or difierent materials, such as. spring steel, are not required.Such an arrangement reduces the cost of forming the contact and terminaland of assembly.

Other advantages and objects of the invention will be apparent and bestunderstood from the accompanying drawings in which: v

Fig. 1 is a top plan view of a duplex plug receptacle having a portionof its cover broken away and which embodies the invention; v

Fig. 2 is a section view taken along the line 2-2 of Fig. 1;

Fig. 3 is a top plan view of a contact and terminal strip embodying theinvention; V

Fig. 4 is a side elevation of the contact and terminal strip shown inFig. 3;

, Fig. 5 is an end view of the contact andjterminal strip shown in Fig.3;

Fig. 6 is a section view taken along the line 6-6 of Fig. 3; and

Fig. 7 is a plan View of a blank from which the contact and terminalstrip shown in Fig. 3 is formed.

' Referring to the drawings in'detaiLand toFig. 1 in particular, thereis a duplex wiring receptacle 10 which includesa hollow base 11, a cover12 and a supporting strap 13 which are held together in the usual mannerby rivets or screws (not shown). V v The base 11 of the receptacle has araised central boss 14 which extends lengthwise on the interior thereof.The boss 14 inconju'nction with a mating boss 15 on the lower surface ofthe cover divides the receptacle into two chambers, each of whichcontains a contact and terminal strip 16. The supporting strap 13extends through a groove in the boss 15 on the cover and projects beyondthe receptacle at the ends thereof.

As is shown best in Figs. 3 through 7, the contact and terminal strip 16is formed from a blank of electrically conductive material, such asbrass or the like. A set of opposing spring contact elements or fingers17 are formed at each end of a central portion 18 by bending the ends ofthe blank to bring the fingers of each set of contact elements intoopposing relation. The tops of the contact elements of each set areflared outwardly to permit a rial from which the blank is formed causesthe contact elements to engage with the contact blade with a springaction.

The central portion 18 of the strip which serves as a terminal forconnecting a conductor wire to the strip, is disposed in a verticalplane and has wire-guiding grooves 19 formed at the ends thereofadjacent each set of contact elements. A supporting leg 20 is bent upwardly from the lower edge of the central portion of the strip at thecenter thereof and extends inwardly therefrom.

Arms 21 are connected to the supporting leg at the outer end thereof andextend from each'side of the leg lengthwise of the central portion ofthe strip to a point beyond the Wire-guiding grooves formed therein. Thearms extend outwardly and downwardly from the leg in a transversedirection and are disposed in angular relation to the plane of thecentral portion of the strip. When the contact and terminal strip 16 'isassembled in the base of the receptacle, the outer side of the centralportion of the strip bears against an outer side wall of the base withthe lower edges of the arms abutting the central boss at the point whereit joins the bottom of the base.

A wire-engaging member 22 is connected to the top of each of the arms atthe outer end thereof. The wireengaging members extend lengthwise inopposing relation to the central or terminal portion of the strip andthe wire-receiving grooves therein. The wire-engaging members alsoextend upwardly and inwardly, from the arms in a transverse directionand are disposed in angular relation to the terminal portion of thestrip,ywith the angle of the wire-engaging members relative to theterminal portion of the strip being somewhat greater than the angle ofthe arms relative to the terminal portion. The lower corner of the topof thewire-engaging member forms a sharp edge 23 which engages with thebared end of a conductor wire when the wire is inserted in one of thewire-guiding grooves between the terminal portion and the wire-engagingmember. The edge of the wire-engaging member is spaced from the terminalportion by a distance slightly less than the diameter of the smallestconductor wire that is to be connected to the receptacle so that thespring pressure of the Wire-engaging-member will hold the wire firmlyagainst the terminal portion and in good electrical contact therewith..The flexing ofthe wire-engaging member will also allow larger diameterwires to be inserted within limits.

The bottom of the base is provided with wire-receiving openings 24 whichare aligned with the wire-guiding grooves in the terminal portions ofthe strips so that the bared end of the conductor wire can be insertedthrough the. base and between the wire-engaging member and the terminalportions of the respective strips therein. Adjacent each of the wireinsertion openings, elongated openings 25 are provided in the basethrough, which a tool maybe inserted to engage with the. wire-engagingmember to release it fromengagement with the conductor wire.

The cover of the receptacle is provided with the usual pairs of spacedopenings 26 through which the contact blades of an attachment plug maybe inserted into engagement with the contact elements on two of thestrips in the customary manner.

A blank suitable for forming the contact and terminal strips 16 is shownin Fig. 7. The blank may be stamped from a flat strip of the conductivemetal and then be shaped to the desired configuration by suitableforming dies. The metals usually used for forming contact and terminalstrips will provide sufiicient spring action for the functioning of thewire-engaging members as described above. Thus, the, spring action ofthe wireengaging members isobtainedwithoutthe use ofseparate parts madefrom special material, such as spring ,"steeli,

When the bared end'of aconductor'wire' isinserted through-tone.ofthetopenings inthe base and between. the wire-engaging member andterminal portion of the strip,

the wire-engaging member flexes upwardly to permit" entry of the wireand'the barediend of the wire is forced, against the terminal portion ofthe strip by the wire engaging member, as described: above. However, ifa downward pull is exertedon the wire, the sharp corner of the wireengaging member bites into the wire and preventswithdrawal 'of the wire.fThe downward pull on the wire tends to bend theend of the wire-engagingmember downwardly and toward the terminal portion of the strip, withrtheresult that the wire is clamped more tightly between the wire-engagingmember and the terininal portion of thestrip; 'Such bending of the wireengaging member is resisted bythe arms which are in engagement with theboss in the base. In addition, the engagement of the arms with the bossin the base tends to minimize distortion or twisting of thewire-engaging members by repeated insertion of a wire or releasing toolsthrough the openingsin the base. 7 l V i It will be understood thatvarious changes and modifications may be made-in the particularembodiment of the invention illustrated and described herein withoutdeparting from the scope of the following claims,

I claim: 7 1 i 1. In a combined contact and pressure-lock terminal foran electrical wiring device, the improvement which comprisesastrip ofelectrically conductive material, said strip including a terminalportion having a flat face with a wire-guiding groove formed therein,said groove ex: tendingtransversely across said face 'of. the terminal4. In a combined contact andpressure-lock terminal for an electricalwiring device, the improvement which comprises a strip of electricallyconductive material, said strip including a terminal portion having aflat face and wire-guiding grooves formed at the ends of said face, saidgrooves extending transversely across the face of said terminal portion,a leg' integrally connected to the terminal portion at'a pointintermediate the grooves, said leg extending from the terminal portionin angular relation' to the flat face thereof and having an end spacedfrom said face, arms integrally connected to 'said end of the leg andextending lengthwise in opposite directions therefrom in opposingrelation to the terminal portion,

said arms also extending outwardly and downwardly from said leg in atransverse direction and being disposed at an angle with respect to theface of the terminal portion and a wire-engaging member integrallyconnected to each of said arms, each of said wire-engagingmembers'extending toward the face of the terminal portion in opposingrelation to one for the wire-guiding grooves and being disposed at anangle of less than ninety degrees with'resp'ect to the face of theterminal portion, said wire-engaging members having ends spaced from theface of the terminal portion by a distance less than thediamportion, aleg integrally connected to the terminal ,por-

tion at a point spacedfrom said groove, said leg extending from theterminal portion in angular relation to the flat face thereof and havingan end' spaced from said face, an arm integrally connected to said endof the leg and extending lengthwise therefrom in opposing relation tothe face of the terminal portion, said arm also extending outwardly anddownwardly fromsaid leg in a transverse direction and being disposed atan-angleqivith respect to the face of the terminal portion and awire:

engaging member integrally connected to the .arm and extending towardthe face of the terminal portion in opposing relation to thewire-guidinggroove, said'wire: engaging member being disposed at an angle'of'lessthan ninety degrees with respect to the face of the terminal portion andhaving an edge spaced'from the face of the terminal portion by adistance less than the diameter of a bare conductor wire. V r

' 2. In a-combinedcontact and pressure-lock terminal, the improvementas'defined in claim l wherein the wire.-

engaging member and the arm are disposedat difierent angles with respectto the face of the terminal portion. 3. In a combined contact andpressure-locktterminal for an electrical wiring device, the improvement.asdefined in claim 1 which includes a pair of spaced spring contactfingers integrally connected to the terminal portion of the stripadjacent the wire-guiding groove.

eter of a bare connector wire. 7

5.- In a combined contact and pressure-lock terminal for an electricalwiring device, theimprovement as defined in claim 4 wherein thewire-engaging members and the arm are disposed at'diflerent angles withrespect to the face of the terminal portion. 7

6.. In'anelectrical wiring device of the character described, theimprovement whichcomprises a housing of insulating material having arecess formed therein, said recess being defined on one side by anupstanding wall and on the. otherfside by an abutment spaced from andopposing said wall,'a combined contact and pressure lock terminal formedfrom a single strip of electrically conductive material locatedv in saidrecess, said stripincluding a'terminal portion having a flat face with awireguiding groove formed therein, said terminal portion being disposedagainst theiupstanding' wall on one side of, the recess with thewire-guiding groove, being aligned with a.wire-receiving opening inthehousing, a leg extending inwardly from the terminal portion of the stripand toward the other side of the recess, an arm carried by the leg andextending lengthwise therefrom in opposing relation to the terminalportion of the strip, said arm also extending outwardly and downwardlyfrom the'leg in angular relation to the terminal portion of the'stripand engaging with the abutment at the other-side of the ofthe strip.

References Citediin the file of this patent UNITED STATES PATENTS2,705,785 Benander Apr. 5,]1955 12,720,634 'Hart Oct. 11, 1955 2,773,248Smith Dec. 4, '1956 1a can,

